1. Technical Field
The embodiments herein generally relate to medical devices, and, more particularly, to implantable spinal fixation systems used for connecting cylindrical rods to each other in spinal columns.
2. Description of the Related Art
The spinal column is a highly flexible structure comprising bones and connective tissue. While, the spine is capable of multiple degrees of motion, spinal injuries or anatomical irregularities may result in spinal pathologies which limit this range of motion. Orthopedic surgeons often aim to correct spinal irregularities and restore stability to injured portions of the spine through immobilization of spinal components. Several conventional spinal implant stabilization systems such as spinal cross-connectors exist to assist doctors in immobilizing the spine. These conventional systems often include components having connective structures such as elongated rods which are positioned on opposite sides of the portion of the spinal column intended to be immobilized and are usually implemented with screws and hooks to facilitate segmental attachment of these connective structures to the posterior surfaces of the spinal laminae, through the pedicles, and into the spinal vertebral bodies. Ideally, these connective components provide the necessary mechanical stability to achieve spinal immobilization.
Most existing spinal cross-connectors consist of rods, plates, and bars linked to the longitudinal rods by coupling mechanisms with set screws, nuts, or a combination of each. Generally, these spinal cross-connectors require several sub-components and fixation instruments to build the structures. Each additional required component or instrument necessary to assemble the connectors typically adds to the complexity and time of the surgical procedure and may effect the successful outcome of the procedure. Examples of spinal cross-connectors are described in U.S. Pat. Nos. 5,312,405; 5,334,203; and 5,498,263, the complete disclosures of which, in their entireties, are herein incorporated by reference.
However, most conventional spinal cross-connectors generally have a limited range of motion constrained by planes or axis. This tends to make them difficult to connect to the longitudinal member (i.e., transverse rod or bar) or appropriately place them around the spinal anatomy. Spinal cross-connectors usually have 3-6 degrees of freedom of movement. Accordingly, there remains a need for a new spinal cross-connector capable of having an increased number of degrees of freedom of motion and which can be easily constructed and used by a surgeon during a spinal surgical procedure.